I got my hands on an AValue EPD-42S — a 42-inch e-ink display running Android 5.1 on an NXP i.MX 7Dual. The display is 2880x2160, 16-level grayscale, no backlight, and holds its image at zero power. Perfect for a wall-mounted dashboard or photo frame.
I wanted to use the OpenDisplay protocol to push images to it over WiFi from any server on my network. OpenDisplay had a Python library for BLE communication, but no WiFi support. And there was no Android client at all.
So I built both.